One Fibrodysplasia Ossificans Progressiva Trial is on Hold but Another has Shown Promise

Ipsen is a pharmaceutical company based out of Paris. Sadly, they have just announced that they have pressed pause on not one but two studies for fibrodysplasia ossificans progressiva (FOP). FOP is an ultra-rare condition which causes bones to grow within the muscles. It progressively leads to disability and decreases life expectancy.

The Therapy

The reason for the pause is due to data that showed the therapy was unlikely to be successful. When Ipsen acquired the therapy, called palovarotene, they announced they were expecting to file for approval in the second half of last year. This drug is a molecule that researchers believe helps to regulate one of the proteins affecting the growth of the skeletal system.  The hope was that it could serve as a therapeutic option for episodic flare-ups for patients. Assuming approval, the company expected to launch the treatment in the middle of this year.

Now, that is unlikely to happen. However, that also doesn’t mean that they are completely giving up on this investigative therapy. The trials for this drug are still active even though dosing has been put on hold. The trials are still active because the researchers have not discounted the showcased evidence of therapeutic activity.

The pause on trials including this drug technically began in December when a partial hold was placed by the FDA for patients (FOP and multiple osteochondromas) participating in palovarotene trials who were under the age of 14. This initial hold was due to data which showed that the growth plate was closing early in young FOP patients treated with the drug.

So what is going to happen next? Ipsen is working to analyze their data and discussing recommended next steps with regulators. Hopefully, a revised version of this trial can begin soon.


It’s not all bad news though. Just two weeks before Ipsen’s pause, Regeneron announced extremely positive findings for a study of FOP. They’ve been working on this investigation for the past two decades and they believe it could become the very first approved therapy specifically for FOP.

It was a mid-stage, placebo-controlled study of an antibody in adult FOP patients.

In treated patients, there were 90% fewer bone lesions developed than those who were given placebo. For new as well as existing lesions, there was a 25% decrease. FOP flare-ups were documented in 10% of the treated patients versus a total of 42% of those who were given placebo.

Next steps for this company are to discuss filing with the FDA. They are also planning on beginning a pediatric investigation of this drug.

You can read more about these investigative therapies here.

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